The AD736 is a low power, precision, monolithic true rms-to-dc converter. It is laser trimmed to provide a maximum error of 0.3 mV 0.3% of reading with sine-wave inputs. Furthermore, it maintains high accuracy while measuring a wide range of input waveforms, including variable duty cycle pulses and triac (phase) controlled sine waves. The low cost and small physical size of this converter make it suitable for upgrading the performance of non-rms "precision rectifiers" in many applications. Compared to these circuits, the AD736 offers higher accuracy at equal or lower cost. The AD736 can compute the rms value of both ac and dc input voltages. It can also be operated ac coupled by adding one external capacitor. In this mode, the AD736 can resolve input signal levels of 100 V rms or less, despite variations in temperature or supply voltage. High accuracy is also maintained for input waveforms with crest factors of 1 to 3. In addition, crest factors as high as 5 can be measured (while introducing only 2.5% additional error) at the 200 mV full-scale input level. The AD736 has its own output buffer amplifier, thereby providing a great deal of design flexibility. Requiring only 200 A of power supply current, the AD736 is optimized for use in portable multimeters and other battery powered applications. The AD736 allows the choice of two signal input terminals: a high impedance (1012 ) FET input which will directly interface with high Z input attenuators and a low impedance (8 k) input